1. Field of the Invention
This invention relates to a method of rehabilitating underground pipes with a lining comprising a helically wound liner pipe made of a synthetic resin, this comprises the steps of winding a strip of a synthetic resin into a helical shape around a virtual cylinder, so that the side edges of the wound strip are interengaged with each other, and continuously introducing the helically wound liner pipe hereafter referred to as a "liner pipe", into an underground pipe while the liner pipe is being advanced inside the underground pipe, and then fixing the leading end of the liner pipe to the underground pipe and further advancing the liner pipe being formed inside the underground pipe so that the wound strip is allowed to slide around the virtual cylinder with is side edges still interengaged with each other to result in a gradual progressive increase in the diameter of the liner piper toward the winding machine end.
2. Description of the Related Art
The method of forming such helical pipes has already been disclosed in Patent literature, see for instance European Patent Office Publication No. 0001894 in the name of Ri Loc Hong Kong Limited, or Patent Co-operation Treaty Publication No. WO85/03755 in the name of Rib Loc Hong Kong Limited which related to a modification of the system, and see particularly Patent Co-operation Treaty Publication No. WO89/01588 in the name of Rib Loc Australia Pty. Ltd. which related to restraining means for such a pipe structure to control the progressive expansion of the helically wound liner pipe in the underground pipe.